Self-retracting mechanized syringe and methods of use

ABSTRACT

A self-retracting syringe has an injection assembly and a retraction assembly. The injection assembly has a housing, a spring rest, and a spring that is restrained initially in compression between the housing and the spring rest. A plunger rod is disposed inside the coil of the spring. A coupler in contact with the spring rest and the plunger rod releasably couples the plunger rod to the spring rest. When a latch is released, the plunger rod moves distally to urge a seal forward, which seal movement causes a hypodermic needle to extend and a medicament to be expelled through the hypodermic needle. A retraction assembly returns the hypodermic needle into the syringe body after the medicament is expelled. Embodiments of retraction assembly provide an inlet through which fluid may be introduced into the syringe through said hypodermic needle. Methods for filling the syringe are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This disclosure is a divisional application of U.S. application Ser. No.16/158,715, filed Oct. 16, 2018, which claims the benefit of U.S.Provisional Application No. 62/572,645, filed Oct. 16, 2017. Eachapplication, publication and patent listed in this paragraph is herebyincorporated herein by reference in its entirety.

BACKGROUND Technical Field

The present disclosure is related to an automatic injection andretraction syringe. More particularly, the disclosure is related to amanually operable mechanism which upon actuation by the user inserts ahypodermic needle into living tissue, injects a liquid therapeuticsubstance and immediately thereafter permanently retracts the hypodermicneedle within the device so as to render the hypodermic needleinaccessible.

Background

Communicable blood-borne diseases such as HIV, hepatitis, and others,exist within the general population. The serious health threat posed byexposure to these diseases has increased the desire to preventinadvertent needle sticks after the administration of injectablesubstances. Indeed, the desire to avert the transmission of blood-bornediseases brought about through exposure to contaminated hypodermicneedles has prompted legislation mandating the provision of means bywhich the risk of such exposure is mitigated. Many prior art injectiondevices include various strategies to mitigate the risk of inadvertentneedle stick injuries and the transmission of pathogens.

In addition to the foregoing, there is a growing trend to affordpatients that must receive injections as part of a medical therapy themeans whereby they may self-medicate. Automatic self-injection deviceshave become increasingly commonplace. They are widely recognized as avaluable means to enable medically untrained users to administerinjections while avoiding the emotional trauma associated with the useof conventional syringes. It has been proven that providing injectablesubstances in self-injection devices increases patient compliance withtheir prescribed therapy and thereby improves medical outcomes. Amongthe various strategies for mitigating the risk of needle stick injuryand providing the patient a preferred alternative for self-injection, anumber of automatic injection devices incorporate self-retractinghypodermic needles.

Thus for the reasons cited above, among others, there remains a presentand increasing need for improved automatic self-injection technology.

SUMMARY

An injection and retraction syringe comprises an injection assembly anda drug-Tillable retraction assembly securable to the injection assembly;the injection assembly comprising a housing, a plunger rod, a powermeans, a latch, an unlatching means, a spring rest, and a coupleroperable to engage and disengage from the plunger rod. In the injectionand retraction syringe described, the power means, preferably comprisinga spring, resides internal to the housing and in contact with the springrest; the spring rest resides in contact with coupler; coupler remainsengaged with the plunger rod so long as the coupler remains in contactwith the housing. Further, in the injection and retraction syringedescribed, a fluid containment means is provided comprising at least onedynamic seal, a fluid containment chamber and a hypodermic needle whichis permanently attached to the fluid containment chamber. The plungerrod is configured to impinge upon the dynamic seal upon actuation of thesyringe and transfer force thereto. A sealable compartment is providedwhich houses the hypodermic needle and a return spring; the returnspring resides in a partially biased condition and abuts the fluidcontainment chamber. The dynamic seal is operable to contain a fluidwithin the fluid containment chamber and displace the fluid out of thechamber through the hypodermic needle. A removable cover is provided anddisposed about the end of the syringe that houses the hypodermic needle.The removable cover cooperates in a slide able and sealed engagementwith the hypodermic needle. Further, the removable cover provides aconnectable and sealable fitting preferably in the form of a taperedsocket configured to receive a means to convey fluid through the cover,through the hypodermic needle and into the fluid containment chamber.Preferably, a means to close the connectable fitting disposed on thecover may be provided. In the injection and retraction syringedescribed, the sealed volume and fluid path may preferably be sterile.An alternative embodiment provides a sub-assembly comprising amedicament container, a hypodermic needle, and a single dynamic seal.The medicament container is disposed internal to a housing andconfigured move axially within the housing in a sliding relationshipwithin the interior of the housing. In this embodiment, the dynamic sealis configured to travel axially in a slide able relationship within theinterior of the medicament container. A hypodermic needle is permanentlyaffixed at the distal end of the syringe body medicament container andprovides a conduit through which fluid may pass into and/or out of themedicament container. A retraction spring is disposed distal to and incontact on the return spring's proximal end with the exterior distalsurface of the medicament container. The return spring is also incontact on its distal end with the interior, proximally-disposed surfaceof the housing whereupon the return spring is retained axially in apartially biased condition. In its ready-to-use state, the medicamentcontainer is urged in the proximal direction by the partially biasedreturn spring and causes the medicament container to rest upon adistally disposed interior surface.

There is disclosed further a plurality of methods of producing aready-to-use combination of medicinal fluid and a mechanism forautomatically injecting the medicinal fluid into living tissue. In themethods described, the mechanism being prepared could be theself-retracting mechanized syringe describe above, although the methodsdisclosed are not limited to use of a particular syringe. In one methoddescribed, the medicinal fluid is filled into the fluid containmentchamber of the present invention by affixing a fluid transfer device tothe connectable and sealable fitting disposed on the cover andtransporting the fluid from the fluid transfer device proximally intothe fluid containment chamber through the hypodermic needle provided bythe present invention.

DRAWINGS

Non-limiting embodiments of the present disclosure are described by wayof example in the following drawings, which are schematic and are notintended to be drawn to scale:

FIG. 1 is an exterior front elevation view of an exemplary embodiment ofa self-retracting mechanized syringe according to the presentdisclosure.

FIGS. 2 and 3 are exterior front elevation views of the two majorsubassemblies of an embodiment of the self-retracting mechanized syringeaccording to the present disclosure prior to final assembly.

FIGS. 4A and 4B show a cross section of the upper subassemblyillustrated in FIG. 2 with the section taken along the long axis.

FIGS. 5A and 5B show a cross section of the lower subassembly shown inFIG. 3 with the section taken along the long axis and in the same planeas FIG. 4 .

FIGS. 6A and 6B show a cross sectional view of the fully assembledautomatic injection and retraction syringe of FIG. 1 with the sectiontaken along the long axis.

FIGS. 7A through 7F show further details of the upper region of uppersubassembly of FIGS. 2 and 4 in cross section.

FIGS. 8A through 8C are section views taken along the long axis anddescribe an alternative embodiment of the upper subassembly.

FIGS. 9A and 9B show further details of the middle region of the uppersubassembly common to embodiments described in FIGS. 2, 4, 7 and 8 .

FIGS. 10A through 10C show further details of the upper and lowerregions of the lower subassembly of FIGS. 3 and 5 .

FIG. 11 shows a partial cutaway perspective view of, and further detailsof upper subassembly 200.

FIGS. 12 through 19 provide cross sectional views of a first embodimentof the automatic injection and retraction syringe during notable statesand various transitional states during usage sequence.

FIG. 12 illustrates the automatic injection and retraction syringe in aready-to-use state whereupon it is filled with medicament and providedto the user.

FIGS. 13A and 13B illustrate the automatic injection and retractionsyringe during and after cap removal.

FIGS. 14A and 14B illustrate the automatic injection and retractionsyringe transitioning into state of activation prior to actuation.

FIGS. 15A and 15B illustrate the automatic injection and retractionsyringe while activated and transitioning into state of actuation priorto plunger rod travel.

FIGS. 16A and 16B illustrate the automatic injection and retractionsyringe transitioning into state of full hypodermic needle extension andprior to dose delivery.

FIGS. 17A and 17B illustrate the automatic injection and retractionsyringe transitioning into state of full dose delivery prior to releaseof plunger rod.

FIGS. 18A through 18D illustrate the automatic injection and retractionsyringe transitioning into state of plunger rod release just prior toneedle retraction.

FIGS. 19A and 19B illustrate automatic injection and retraction syringetransitioning into state of needle retraction.

FIG. 20 is an exploded view of the upper subassembly of FIGS. 2 and 4 .

FIG. 21 is an exploded view of the lower subassembly of FIGS. 3 and 5 .

FIGS. 22A through 22E illustrate a method for filling the medicamentinto the automatic injection and retraction syringe.

FIGS. 23A through 23C illustrate a method for filling the medicamentinto the lower subassembly and completing final assembly of the syringe.

FIG. 24 illustrates the front elevation of a second embodiment of thepresent invention.

FIGS. 25A and 25B illustrate a cross section of a second embodiment ofthe present invention with the section taken at the center axis.

FIGS. 26A and 26B illustrate a cross section of a second embodiment ofthe present invention and provides additional detail of the proximalend.

FIGS. 27A through 27C illustrate a partial cross section of the proximalend of a second embodiment of the present invention and provide furtherdetail of a rotating locking/unlocking actuation button.

FIGS. 28A and 28B illustrate a cross section of a second embodiment ofthe present invention and provides additional detail of the distal end.

FIGS. 29A through 29C illustrates a cross section of a second embodimentof the present invention and further illustrates the operation of anattached plug configured to seal the distal end of removable cap.

FIGS. 30 through 35 provide cross sectional and pictorial views of asecond embodiment of the present invention during notable states andillustrate various transitional states during the usage sequence.

FIGS. 30A through 30C illustrate a second embodiment of the presentinvention during and after cap removal.

FIGS. 31A through 31D illustrate a second embodiment of the presentinvention as the actuation button transitions from an inactivated stateto an activated state.

FIGS. 32A and 32B illustrate a second embodiment of the presentinvention as the activated button is actuated.

FIGS. 33A and 33B illustrate a second embodiment of the presentinvention transitioning into the state of full hypodermic needleextension and prior to dose delivery.

FIGS. 34A and 34B illustrate a second embodiment with the hypodermicneedle fully extended and transitioning into the state of full dosedelivery.

FIGS. 35A through 35D illustrate a second embodiment in a state ofplunger rod release and prior to syringe retraction.

FIGS. 36A and 36B illustrate a second embodiment as the plunger rod andsyringe assembly transition to the retracted state.

FIG. 37 is an exploded view of a second embodiment of the presentinvention.

FIGS. 38A through 38E illustrates a method of filling the medicamentinto a second embodiment of the present invention and sealing the end ofthe removable cap.

INDEX OF REFERENCE NUMERALS Reference Element 100 automatic injectionand retraction syringe 200 upper subassembly 201 button 202 sleeve cap203 button return spring 204 latch 205 needle insertion/fluid injectionspring 206 housing 207 spring rest 208 coupler 209 plunger rod 210sleeve 211 housing relief 212 --not used -- 213 aperture 214 latchproximal face 215 housing annular flange 216 sleeve retaining feature217 sleeve cap shoulder 218 proximally disposed tip of latch finger 219cam 220 latch finger 221 latch shoulder 222 plunger rod shoulder 223fulcrum point 224 alternative sleeve cap 225 spring rest flange 226housing bore 227 spring rest bore 228 sleeve cap window 229 button arm230 annular engaging surface 231 plunger rod groove 232 plunger rodflange 233 housing male snap fit feature 234 housing counterbore 235distally disposed surface 236 male snap fit feature on sleeve cap 237female snap fit feature on sleeve 238 sleeve longitudinal ribs 239housing longitudinal rib 240 -- not used -- 241 latch snap fit feature242 latch snap fit receiver 300 lower subassembly 301 syringe body 302upper dynamic seal 303 fluid medicament 304 lower dynamic seal 305needle retraction spring 306 retainer 307 nose 308 hypodermic needle 309cap 310 cap seal 311 female socket 312 guidance track 313 receivingaperture 314 -- not used -- 315 buttress surface 316 syringe bodyaperture 317 retainer barb 318 cap retention feature 319 syringe bodyretention feature 320 cap gripping feature 321 plug 322 medicamentcontainment chamber 323 retainer flange 324 retainer flange proximalsurface 325 retainer flange distal surface 326 beveled end of hypodermicneedle 327 hollow protrusion 328 retainer neck 329 retainer annularsecurement feature 330 lower dynamic seal securement feature 331 noseaperture 332 proximal end of hypodermic needle 333 lower dynamic sealaperture 334 syringe body retaining surface 335 syringe graduationmarkings 336 viewing window 337 nose annular ring 338 syringe bodyannular groove 339 tapered seal surface on nose 340 tapered sealingsurface on syringe body 341 seal feature on nose 342 dynamic sealannular ribs 400 fluid transfer mechanism 500 fill nozzle 600 push rod700 syringe 701 button 702 button retainer seal 703 button retainer 704latch 705 label 706 needle insertion/fluid injection spring 707 plungerrod 708 spring rest 709 coupler 710 inner housing 711 inner housing cap712 dynamic seal 713 outer housing 714 fluid medicament 715 medicamentcontainer 716 hypodermic needle 717 cap 718 retraction spring 719 needleseal 720 cap plug 721 inner housing buttress surface 722 spring restbearing surface 723 inner housing bore 724 latch retaining feature 725plunger rod resting surface 726 button retainer slot 727 button arm 728slot tip 729 slot buttress surface 730 gripping surface 731 graphics 732button retainer snap fit feature 733 outer housing snap fit feature 734cam 735 latch finger 736 syringe buttress surface 737 rib shoulder 738proximally-disposed interior surface of syringe body 739 distal end ofinner housing 740 distal opening of inner housing 741 outer housingcounterbore shoulder 742 proximal surface of latch 743 distal surface ofbutton retainer 744 annular ring 745 receiving groove 746 hinge 747 capplug body 748 female socket 749 proximal opening of hypodermic needle750 engaging surface of spring rest 751 outer housing bore 752 -- notused -- 753 distal surface of inner housing cap 754 sharp tip ofhypodermic needle 755 outer housing distal aperture

DETAILED DESCRIPTION

As used in this disclosure, the term “proximal” defines the end of thedescribed embodiments opposite the hypodermic needle; that is, the axialdirection opposite that of the needle.

The term “distal” similarly defines the needle end of the describedembodiments; that is, the axial direction towards the needle. It shouldalso be noted that the terms “first”, “second”, “third”, “upper”,“lower”, and the like may be used herein to modify various elements.These modifiers do not imply a spatial, sequential, or hierarchicalorder to the modified elements unless specifically stated.

Similarly, the term “enable” is hereinafter used to describe the actionnecessary to allow the subject of the present disclosure to advance tothe next step in the usage sequence. The term “activation” ishereinafter used to describe the action necessary to cause the subjectto become active, i.e. able to respond to a triggering action. The term“actuation” is hereinafter used to describe the action necessary totrigger the injection process.

Referring to the figures and in particular to FIGS. 1 and 6 , anexemplary embodiment of an automatic injection and retraction syringe100 according to the present disclosure is shown. The automaticinjection and retraction syringe 100 is generally symmetric about itslong axis. Upon actuation, the automatic injection and retractionsyringe 100 is adapted to automatically extend a hypodermic needle 308from within the assembly into tissue at an injection site, displace thefluid medicament 303 through the hypodermic needle 308, andautomatically retract the hypodermic needle 308 after the injection iscompleted.

A general aspect of operation of this disclosure is the relationshipbetween the viscosity of the fluid medicament 303, the inner diameter ofthe hypodermic needle 308, the force applied upon the upper dynamic seal302 by the needle insertion/fluid injection spring 205 by way of theplunger rod 209, the force applied by the needle retraction spring 305upon the lower dynamic seal 304, and the friction force resistingmovement of the lower dynamic seal 304 along the interior of the syringebody 301. The friction forces must be sufficiently low, the bore of thehypodermic needle 308 sufficiently small, the force of the needleretraction spring 305 sufficiently low as compared to the force of theneedle insertion/fluid injection spring 205, and the viscosity of themedicament 303 sufficiently high so that the upper dynamic seal 302, thelower dynamic seal 304, the fluid medicament 303 and the hypodermicneedle 308 will traverse distally to the end stop position before thefluid medicament 303 escapes the hypodermic needle 308.

An embodiment provides, for the convenience of assembly, twosubassemblies hereinafter described as the “upper subassembly” and“lower subassembly” and are assembled to complete the automaticinjection and retraction syringe 100. Other assembly strategies areallowable within the scope of the claims. Referring to FIGS. 2 and 4 ,an embodiment of the upper subassembly 200 is described. The uppersubassembly 200 comprises a trigger preferentially embodied as a button201, a sleeve cap 202, a button return spring 203, a latch 204, a needleinsertion/fluid injection spring 205, a housing 206, a spring rest 207,a coupler 208, a plunger rod 209, and a sleeve 210. Upon assembly of theupper subassembly 200, the needle insertion/fluid injection spring 205resides in a state of substantially full compression, axially coincidentwith and exterior to the plunger rod 209. The needle insertion/fluidinjection spring 205 is confined axially on one end by a distallydisposed interior surface of the housing 206, and at the opposite end bya proximally disposed surface on the spring rest 207. Referring to FIGS.4 and 7E, latch 204 provides, preferably, a plurality of latch finger220. Latch finger 220 provides a latch shoulder 221 that engages with aplunger rod shoulder 222 disposed on the plunger rod 209, and therebyretains the needle insertion/fluid injection spring 205 in an energizedstate until engagement between the plunger rod 209 and the latch 204 isdefeated by the button 201. In one embodiment, the latch 204 and thehousing 206 are separate components. The two components may beconsolidated into a single component in an alternative embodiment. Aswill be more particularly described below, while referring to FIG. 11 ,an embodiment of the housing 206 provides male snap fit feature 233allowing for permanent physical attachment, for example by interferencesnap fit engagement, with the lower subassembly 300.

Referring to FIGS. 4 and 9 , spring rest 207 resides in contact with atleast one coupler 208 that engages radially with a correspondingretaining feature disposed on the plunger rod 209. In an embodiment, thecoupler 208 comprises a sphere. Upon assembly of the upper subassembly200, the coupler 208 remains trapped radially between a retainingfeature, which may be, for example, a groove 231 disposed upon theexterior surface of the plunger rod 209, and the bore 226 of the housing206.

In an embodiment, and as illustrated in FIGS. 4, 7 and 11 , the triggermeans is embodied in the form of a button 201. The button 201 isretained in an axial sliding fit relationship within the sleeve cap 202with a portion of the button 201 protruding proximally through anaperture 213 in the sleeve cap 202. The sleeve cap 202 is permanentlysecured to proximal end of the sleeve 210. Means of securement may beaccomplished, for example, by interference fit or snap fit. Disposed onthe button 201 and oriented in the distal direction is an unlatchingfeature, such as a protrusion acting as a cam 219 responsible forengaging with latch finger 220 of latch 204 to force the latch finger220 radially outward upon the application of force upon the button 201in the distal direction. In an alternative embodiment of the presentdisclosure, the button 201 as an independent component is eliminated andthe distally-disposed cam 219 that cooperates with the latch 204 isincorporated as an integral element of the sleeve cap 202. These twoalternative embodiments for actuating the injection sequence will bedescribed in further detail below while referencing FIGS. 7 and 8 .

Continuing with FIGS. 4 and 7 , a button return spring 203 residesinternally to the button 201 in a partially biased state confined on theproximal end by a distally disposed surface 235 on the button 201. Thedistal end of the button return spring 203 is confined by a proximallydisposed face 214 on the latch 204. As will be described in greaterdetail while referencing other figures below, the button return spring203 also serves to urge the sleeve 210 and the sleeve cap 202 in theproximal direction. Also while referencing other figures below, proximaltravel of the sleeve 210 under influence of the button return spring 203is limited by axial interference with a cooperating feature disposed onthe exterior of the housing 206. After final assembly of the automaticinjection and retraction syringe 100, application of distally appliedforce on the sleeve 210 while the housing 206 is held stationary causesthe sleeve 210 to travel distally relative to the housing 206 andfurther biases the button return spring 203. The button return spring203 thus serves two functions; it urges the button 201 proximally andalso the sleeve 210 proximally. The sleeve 210 also serves as a handgrip during use of the automatic injection and retraction syringe 100.More detail regarding the sleeve 210 and the button 201 functionality,interdependency, and embodiment options will be described in furtherdetail below while referencing other figures.

Referring to FIG. 5 , the lower subassembly 300 of the presentdisclosure comprises a syringe body 301, an upper dynamic seal 302, alower dynamic seal 304, a needle retraction spring 305, a retainer 306,a nose 307, a hypodermic needle 308, a cap 309, and a cap seal 310. Thecap 309 may include a female socket 311, preferably dimensioned to becompliant with what is known to those skilled in the art as a femaleLuer taper, disposed distal to the cap seal 310. Referring to FIG. 22 ,preferably, installation of the fluid liquid medicament 303 into thefully-assembled automatic injection and retraction syringe 100 may beaccomplished by engaging a fluid transfer mechanism 400, for example asyringe with a male Luer slip end, with the female socket 311 in a fluidtight taper lock relationship, and transferring the fluid from the fluidtransfer mechanism 400 into the drug containment chamber, herein definedfor the present embodiment as the space interior to the syringe body301, proximal to the lower dynamic seal 304, and distal to the upperdynamic seal 302, as shown in the figures via the hypodermic needle 308.Referring to FIG. 23 , pursuant to an alternative method of filling theautomatic injection and retraction syringe 100 with fluid medicament303, the upper subassembly 200 and lower subassembly 300 may be providedas separate subassemblies. The medicament 303 may be installed bygravity filling into the syringe body 301 of the lower subassembly 300proximal to the lower dynamic seal 304, and thereafter installing theupper dynamic seal 302. Various methods for gravity filling and sealinstallation are well known to those skilled in the art. As illustratedin FIG. 6 , once the fluid medicament 303 and the upper dynamic seal 302are installed, the lower subassembly 300 is permanently secured to theupper subassembly 200 to form the automatic injection and retractionsyringe 100.

Referring to FIGS. 4, 7, 8 and 11 , two embodiments of a trigger meansare described. FIG. 7 illustrates a cross sectional view of the uppersubassembly 200 in a first embodiment. The upper subassembly 200 and itsconstituents are, preferably and generally, of annular geometrysymmetric about the long axis. In this embodiment, the trigger meansassumes the form of a button 201 retained within the sleeve cap 202. Aportion of the button 201 protrudes proximally through aperture 213 inthe sleeve cap 202. The aperture 213 is sized to provide radialclearance in relation to the button 201, allowing for free axialmovement of the button 201. Referring to FIG. 11 , a means to limitaxial travel of the button 201 within the sleeve cap 202 is provided viaat least one window 228 provided on the sleeve cap 202 and at least onecooperating arm 229 provided on the button 201. The button arm 229 isdimensioned to allow restricted axial travel within the sleeve capwindow 228 thus limiting axial travel of button 201 within the sleevecap 202. The button 201 is urged in the proximal direction throughcontact with the button return spring 203 which is retained in apartially biased condition with its opposite end resting upon theexterior proximally disposed face 214 of the latch 204. The sleeve cap202 and the sleeve 210 are axially aligned and permanently affixedtogether. Preferably, securement is provided by interference fit or snapfit. Referring to FIG. 7 b , one preferred embodiment of snap fitarrangement describes male snap fit feature 236 of sleeve cap 202 andcorresponding female snap fit feature 237 of the sleeve 210. Referringback to FIG. 11 , the sleeve 210 is preferably configured withinternally disposed sleeve ribs 238 which cooperate in an axial slidingfit relationship with corresponding longitudinal rib 239 disposed alongthe exterior of the housing 206. Sleeve ribs 238 in cooperation withhousing rib 239 allow for free axial movement of the sleeve 210 inrelation to the housing 206 while retaining the sleeve 210 in an axiallycoincident relationship with housing 206. This cooperative relationshipbetween sleeve ribs 238 and housing ribs 239 also serves to preventaxial rotation of the sleeve 210 in relation to the housing 206.

Referring to FIGS. 4 and 11 , a housing annular flange 215 and thesleeve retaining feature 216 cooperate to limit the proximal movement ofthe sleeve 210 under the influence of the button return spring 203. Thesleeve retaining feature 216 is preferably smaller in diameter than thediameter of the housing annular flange 215. Thus the proximally-disposedsurface of the sleeve retaining feature 216 impinges upon thedistally-disposed surface of the housing annular flange 215 under theinfluence of the button return spring 203. Upon application of forceupon the sleeve 210 in the distal direction with the automatic injectionand retraction syringe 100 abutting a surface at the syringe's distalend, e.g. the injection site; the sleeve 210 is free to move distally aset distance defined as the offset distance from the sleeve cap shoulder217 to the proximally disposed face 214 of the latch 204. Preferably,the axial travel distance allowed the button arm 229 within the sleevecap window 228 is less than the distance between the proximally disposedtip 218 of latch finger 220 and distally disposed cam 219, thus makinginadvertent contact between the button 201 and the latch 204 impossibleunless the sleeve 210 is moved in a distal direction relative to thehousing 206. The foregoing dimensional relationships between the button201, the latch 204, the sleeve 210, the sleeve cap 202 and the housing206 facilitate a safety utility, whereby actuation of syringe automaticinjection and retraction 100 can only be accomplished by the combinationof distal movement of the sleeve 210 relative to the housing 206 anddistal movement of button 201 relative to the sleeve cap 202.

Again referring to FIGS. 4 and 7 b through 7E, the distally disposed cam219 of the button 201 cooperates with the proximally disposed latch 204.Preferably, the latch 204 provides a plurality of proximally disposed,semi-rigid latch finger 220 radially arrayed about the axis of latch204. The button 201 and the latch 204 are preferably configured in aconcentric relationship sharing the long axis of the automatic injectionand retraction syringe 100. A top view of the latch 204 in the normalstate is shown above FIG. 7D. Referring to FIG. 7C, a latch shoulder 221provides a proximally disposed resting surface for distally disposedplunger rod shoulder 222. As illustrated in FIG. 7D, upon axial movementof the sleeve 210 from a first, proximal position to a second distalposition, cam 219 approximates the proximally disposed tip 218 of latchfinger 220. The cam 219 is configured to engage a radially inwardlydisposed point at the proximally disposed tip 218 of the latch finger220. As illustrated in FIG. 7E, further distal movement of the button201 causes the cam 219 to engage the latch finger 220 and lever thelatch finger 220 radially outward in a defined manner about a fulcrumpoint 223 and disengage the latch shoulder 221 from the plunger rod 209.A top view of the latch 204 in the open state is shown above FIG. 7E.Preferably, the latch 204 is comprised of material of sufficientresiliency to allow for elastic deformation of the latch finger 220during assembly with the plunger rod 209 while also providing sufficientrigidity to support the plunger rod 209 under the force of the energizedneedle insertion/fluid injection spring 205 indefinitely withoutbuckling or yielding under compressive load. One such material may be,preferentially, polycarbonate.

Referring to FIG. 7B, the latch 204 is preferable coupled to the housing206 by way of snap fit engagement. A latch snap fit feature 241 engageswith corresponding latch snap fit receiver feature 242 disposed on thehousing 206.

Referring to FIG. 8 , a second embodiment of the upper subassembly 200is described. In this embodiment, the cam 219 is incorporated into analternative embodiment of the sleeve cap 224. Other cooperativerelationships between the sleeve 210, the alternative sleeve cap 224,the button return spring 203, the housing 206, the latch 204, theplunger rod 209 the needle insertion/fluid injection spring 205, thespring rest 207 and the coupler 208 remain as previously defined. Thusin this embodiment, and as illustrated in FIG. 8C, no activationfunction is afforded; automatic injection and retraction syringeactuation is accomplished solely by distal axial movement of the sleeve210 relative to the housing 206 once the automatic injection andretraction syringe 100 is enabled by removing the cap 309.

Referring to FIGS. 4 and 9 , an embodiment of the upper subassembly 200and more particularly the disengageable coupling relationship betweenthe needle insertion/fluid injection spring 205 and the plunger rod 209is further detailed. A generally annular spring rest 207 resides withinthe interior bore 226 of the housing 206 and exterior to plunger rod209. Referring to FIG. 9B, a spring rest flange 225 is disposed aboutthe perimeter of the spring rest 207 and is dimensioned for axialsliding fit with the housing bore 226. The spring rest bore 227 is sizedfor an axial sliding fit with the plunger rod 209. Preferably, thespring rest 207 is comprised of material of sufficient rigidity toindefinitely survive the strain imposed by the force of the fullyenergized needle insertion/fluid injection spring 205 without yieldingunder compressive load. One such material may be, for example,polycarbonate. The distal end of the needle insertion/fluid injectionspring 205 abuts against a proximally facing surface of the spring restflange 225. The distal end of the spring rest 207 provides an annularengaging surface 230 which impinges upon the coupler 208. The preferablyspherical coupler 208 resides within a plunger rod groove 231 ofcompatible geometry disposed upon the exterior of the plunger rod 209.The spring rest 207 and the coupler 208 thus provide an indirectrelationship between the needle insertion/fluid injection spring 205 andthe plunger rod 209 whereby connectivity between the needleinsertion/fluid injection spring 205 and the plunger rod 209 ismaintained so long as the coupler 208 remains engaged with plunger rodgroove 231. The coupler 208 and the plunger rod groove 231, onceassembled, are dimensioned to provide a sliding fit between the coupler208 and the housing bore 226. So long as the coupler 208 remains engagedwith plunger rod groove 231 and within the housing bore 226, the coupler208 is trapped in engagement with the plunger rod 209. The point ofcontact between the annular engaging surface 230 of the spring rest 207and the coupler 208 resides slightly radially inward from thedistal-most surface of coupler 208. Thus, under the influence ofenergized needle insertion/fluid injection spring 205, the spring rest207 imposes a major force component upon the coupler 208 in the distaldirection and a minor force component directed radially outward.

Referring to FIGS. 4, 6 and 9 , the distal end of the plunger rod 209preferably provides a plunger rod flange 232 dimensioned to provide aneasy running fit with the interior diameter of the syringe body 301 andend-to-end engagement with proximal surface of the upper dynamic seal302.

Referring to FIGS. 9 and 10 , an embodiment of the housing 206 providesa plurality of male snap fit feature 233 disposed about the exterior ofthe housing 206. An embodiment of the syringe body 301 provides aninternally disposed guidance track feature 312 configured to accommodateand provide an axial pilot for male snap fit feature 233 to assureradial alignment with the receiving aperture 313 disposed on syringebody 301. The syringe body 301 or the housing 206, or both, arepreferably comprised of a resilient material capable of elasticdeformation sufficient to allow radial deflection exceeding the radialinterference between the mating snap fit feature 233 and the syringebody 301 during axial engagement of the housing 206 and the syringe body301 during final assembly of the automatic injection and retractionsyringe 100. Referring to FIG. 11 , preferably, the housing 206 providesa relief 211 adjacent to the male snap fit feature 233 to accommodateannular inward deflection of the syringe body 301 during the snap fitprocess.

Referring to FIG. 10B, the syringe body 301 also provides a radiallyinwardly disposed retaining surface 334 configured to receive and retainthe coupler 208 upon disengagement from the plunger rod 209.

Referring back to FIGS. 5 and 10 , the lower subassembly 300 comprises asyringe body 301, an upper dynamic seal 302, a lower dynamic seal 304, aneedle retraction spring 305, a retainer 306, a nose 307, a hypodermicneedle 308, a cap 309 and a cap seal 310. The syringe body 301, theupper dynamic seal 302 and the lower dynamic seal 304 are comprised ofmaterials compatible with the fluid medicament 303. The hypodermicneedle 308 is permanently secured to the retainer 306 in a coaxialrelationship and a defined needle protrusion length. Securement isaccomplished, for example, by insert molding, adhesive bonding or thelike. Referring to FIG. 10C, the proximal end 332 of the hypodermicneedle 308 is disposed within seal aperture 333 provided by the lowerdynamic seal 304 and is configured to provide fluid communication fromthe medicament containment chamber 322, to the open proximal end 332 ofthe hypodermic needle 308. The retainer 306 is permanently affixed onits proximal end to the lower dynamic seal 304. Retention may befacilitated, preferably, by inclusion of retainer annular securementfeature 329 radially disposed about the exterior of the retainer 306 anda geometrically similar lower dynamic seal securement feature 330radially disposed within the interior of the lower dynamic seal 304. Theretainer 306 provides a retainer flange 323 with a proximal surface anda distal surface. The proximal flange surface 324 of the retainer 306approximates or contacts the distal surface of the lower dynamic seal304 and the distal flange surface 325 of the retainer flange 323provides a contact surface for the needle retraction spring 305 to actupon. The length of the retainer 306 from the distal flange surface 325to the retainer barb 317 is defined to establish and sustain a partiallybiased condition of the needle retraction spring 305 with a known forcein its free state. The upper dynamic seal 302 and the lower dynamic seal304 are geometrically and materially configured to provide sufficientcompressive interference with the interior surface of the syringe body301 to assure static and dynamic fluid containment yet exhibit lowdynamic frictional properties during axial movement. The lower dynamicseal 304 and the syringe body 301 are configured to assure frictionforce between the lower dynamic seal 304 and the syringe body 301 isless than the force imposed on the lower dynamic seal 304 via theretainer 306 by the partially biased needle retraction spring 305. Thusin a free condition, the lower dynamic seal 304 is urged into a fixed,proximal position relative to the syringe body 301 defined by theaforementioned length restriction posed by the retainer 306.

Again referring to FIGS. 5 and 10B, an embodiment of the upper dynamicseal 302 is preferably comprised of elastomeric or semi-elastomericmaterial, e.g. butyl rubber, fluorinated ethylene propylene, silicone,etc. Annular ribs 343 of upper dynamic seal 302 are configured tominimize friction in sliding contact with the interior of syringe body301 while preventing leakage of medicament or ingress of microorganisms.

Referring to FIG. 10C, the needle retraction spring 305 resides internalto the syringe body 301 and externally coincident to the retainer 306.The proximal end of the needle retraction spring 305 impinges upon adistally disposed surface 325 of the retainer flange 323; the distal endof the needle retraction spring 305 rests against a proximally facingbuttress surface 315 disposed on the distal end of the syringe body 301.The syringe body aperture 316 is sized to provide clearance for an axialslip fit with the neck 328 of the retainer 306. The retainer 306preferably provides a plurality of distally disposed, radiallydeflectable retainer neck 328 symmetrically configured in an oppositehand relationship about the axis of the retainer. The retainer neck 328exhibits sufficient resiliency to deflect radially inward into a“closed” condition upon application of a radially inward applied force.A distally tapered retainer barb 317 is disposed at the end of retainerneck 328 and is dimensioned to pass through the syringe body aperture316 in the distal direction as retainer neck 328 deflects inwards andbecomes biased to the closed condition during distal movement of theretainer barb 317 through the syringe body aperture 316. As the retainerbarb 317 exits the distal end of the syringe body aperture 316, theretainer neck 328 reflexes outwardly. The retainer barb 317 is sized andgeometrically configured to be prevented from reentering the syringebody aperture 316 under force imposed upon the retainer 306 in theproximal direction by the biased needle retraction spring 305, and whileretainer neck 328 is in a relaxed state. The retainer neck 317 thereforeremains exterior to the distal end of the syringe body 301. The retainer306 functions as securement for the hypodermic needle 308; travel stopfor proximal travel of the lower dynamic seal 304 under influence of theneedle retraction spring 305; and axial guidance to maintain a coaxialalignment of the hypodermic needle 308 with the automatic injection andretraction syringe 100 during distal movement of the hypodermic needle308.

Referring to FIGS. 10 and 21 , an embodiment of the syringe body 301provides graduation markings 335 on the exterior of the syringe body 301indicating the volume of the fluid medicament 303. Preferably,graduation markings are provided in a known and repeatable axial andradial position. The cap 309 provides at least one viewing window 336 ina cooperative location relative to graduation marking 335. The viewingwindow 336 allows visualization of the contents of automatic injectionand retraction syringe 100 once filled with the fluid medicament 303.The cap 309 provides at least one retention feature 318 which cooperateswith a geometrically similar retention feature 319 disposed on thesyringe body 301 to create a separable retaining engagement. Theretaining engagement is defeated by the application of a known andpredictable axial force applied distally to the cap 309 while holdingthe sleeve 210 stationary. While the cap 309 is engaged with the syringebody 301, the sleeve 210 cannot be caused to move in the distaldirection. One utility of the cap 309 is thus a safety feature making itimpossible to activate or actuate the automatic injection and retractionsyringe 100 unless the cap 309 is first removed. Thus removal of the cap309 enables the automatic injection and retraction syringe to beactivated and/or actuated. Also, while the cap 309 remains engaged withthe syringe body 301, radial movement of the cap 309 relative to thesyringe body 301 is inhibited. This radially-retained relationshipbetween the cap 309 and the syringe body 301 serves to establish theradial relationship between the viewing window 336 and the graduationmarkings 335, preferably to allow the graduation markings 335 to be seenthrough the viewing window 336. Referring to FIGS. 10C and 21 , thepreferred embodiment of the cap 309 provides a plurality of grippingfeature 320 disposed about the exterior of the cap 309 to facilitatemanual removal of the cap 309.

Referring to FIG. 10C, an embodiment comprises a nose 307 permanentlyaffixed to the syringe body 301, preferably via interference snap fitand sealed relationship. An annular groove 338 is radially disposedabout the periphery of the syringe body 301 and configured to cooperatewith an annular radial ring 337 of similar geometry inwardly disposedabout the interior surface of the nose 307. A radially disposed andtapered sealing surface 339 on the interior of the nose 307 andcorresponding radially disposed and tapered sealing surface 340 on theexterior of the syringe body 301 are provided. The syringe body annulargroove 338 is offset axially slightly in the distal direction inrelation to radial ring 337 disposed on the nose 307 to urge the nose307 proximally in relation to the syringe body 301 and secure taperedsealing surfaces 339 and 349 into separable annular sealing contact.

Continuing with reference to FIGS. 5 and 10C, an embodiment of the cap309 provides an internal, annular, proximally disposed, hollowprotrusion 327. The proximal end of the hollow protrusion 327 closelyapproximates the distal surface of the retainer 306, thus impeding thedistal movement of the retainer 306, the hypodermic needle 308, and thelower dynamic seal 304, so long as the cap 309 remains engaged with thesyringe body 301. The internal diameter of the hollow protrusion 327 isconfigured to accommodate a cap seal 310 which seals against a portionof the exterior surface of hypodermic needle 308 proximal to the beveledend 326 of the hypodermic needle 308. The cap seal 310 provides a slideable, liquid-tight interface with the exterior surface of hypodermicneedle 308 and a permanently secured, non-sliding sealing engagementwith a portion of the interior surface of hollow protrusion 327. Anembodiment of the lower subassembly 300 provides a separable annularinterference fit between the hollow protrusion 327 and a radially andproximally disposed seal feature 341 of the nose 307. The seal feature341 engages with the exterior surface of hollow protrusion 327 in aseparable interference and sealing relationship. By virtue of thesealing relationship described above and the sealed relationship betweenthe syringe body 301 and the nose 307 described previously, the interiorvolume of the nose is isolated from the exterior environment until thecap 309 is removed.

Again referring to FIG. 10C, the cap 309 further provides a preferablyfrustroconical female socket 311 preferably compliant with the generaldimensional specifications for a female Luer taper. Female socket 311 isdisposed distal to the open distal end of the hypodermic needle and influid communication therewith. The base of the frustroconical cone isdisposed in the distal direction. A plug 321 configured to engage femalesocket 311 in a taper lock relationship may be provided. The plug 321preferably comprises an elastomer or provides an elastomeric constituentwithin a rigid exterior shell.

FIGS. 12 through 20 describe the operational sequence of the firstembodiment of the automatic injection and retraction syringe 100, andparticularly noteworthy states or transitional states in the operationalsequence. As described and illustrated previously, a second embodimentnot shown in the following sequential illustrations comprises analternative sleeve cap 224 that eliminates the activation step andfacilitates actuation solely through distal movement of the sleeve 210in relation to the housing 206.

FIG. 12 is a cross-sectional view of the automatic injection andretraction syringe 100 filled with the fluid medicament 303 and readyfor deployment.

FIG. 13 illustrates removal of the cap 309. The cap 309 is shownpartially removed in FIG. 13A and fully removed in FIG. 13B. Removal ofthe cap 309 is facilitated by gripping the sleeve 210 with one hand, thecap 309 with the other hand, and exerting a force in the axial, distaldirection upon the cap 309 while holding the sleeve 210 stationary.Removal of the cap 309 exposes the nose aperture 331 through which thehypodermic needle 308 may be subsequently extended and retracted.

FIG. 14 illustrates the automatic injection and retraction syringe 100,less the cap 309, transitioning to the activated state. FIG. 14A showsthe state prior to activation;

FIG. 14B describes the state after activation. The automatic injectionand retraction syringe 100 with the cap 309 removed is activated bydirecting the nose 307 against the injection site while grasping thesleeve 210. Application of force upon the sleeve 210 in the distaldirection while the nose 307 abuts the injection site causes the sleeve210 to traverse in distal direction relative to the housing 206,partially biasing the button return spring 203. The cam 219 of thebutton 201 thereby approximates the latch finger 220 as describedpreviously.

FIG. 15 shows the automatic injection and retraction syringe 100, lessthe cap 309, transitioning from the activated state to the actuatedstate. FIG. 15A describes the state wherein the user has placed the nose307 against the injection site and applied sufficient force upon thesleeve 210 to cause the sleeve 210 to telescope distally to achieve theactivated state. FIG. 15B describes the actuated state whereupon thebutton 201 is depressed and cam 219 has forced the latch finger 220radially outward. The plunger rod 209 is thus released and is now freeto move distally under the influence of the needle insertion/fluidinjection spring 205 acting upon the spring rest 207, the spring rest207 acting upon the coupler 208, and the coupler 208 acting upon theplunger rod 209.

FIG. 16 illustrates the automatic injection and retraction syringe 100,less the cap 309, transitioning from the actuated state as described inFIG. 16A to the state whereupon the hypodermic needle 308 is fullyextended as described in FIG. 16B. Upon release of the plunger rod 209,the needle insertion/fluid injection spring 205 forces the spring rest207, and, by virtue of the relationship previously described, thecoupler 208 and the plunger rod 209, in the distal direction. Theplunger rod 209 transfers spring force onto the upper dynamic seal 302.Due to the incompressible nature of the fluid medicament 303, force istransmitted from the upper dynamic seal 302 through the fluid medicament303 to the lower dynamic seal 304 causing the lower dynamic seal 304,the retainer 306 and the hypodermic needle 308 to travel in a distaldirection in tandem with the upper dynamic seal 302 and the fluidmedicament 303. The needle insertion/fluid injection spring 205 in itsenergized state is specified to dominate the force imposed by needleretraction spring 305, thus the needle retraction spring 305 is furtherbiased in the process. Travel continues in the distal direction untilthe retainer 306 contacts the proximally disposed buttress surface 315of the syringe body 301. Once travel is terminated, the hypodermicneedle 308 has been extended externally through the nose aperture 331 apre-defined distance as illustrated in FIG. 16B.

FIG. 17 illustrates the automatic injection and retraction syringe 100,less the cap 309, transitioning from the needle-inserted state asdescribed in FIG. 17A to the state whereupon the fluid medicament 303 isfully dispelled from the automatic injection and retraction syringe 100as described in FIG. 17B. Upon termination of the travel sequencedescribed in the previous paragraph, the lower dynamic seal 304 remainsstationary. The upper dynamic seal 302, under the continued influence ofthe needle insertion/fluid injection spring 205 imposing a force uponthe plunger rod 209 as described previously, continues movement in thedistal direction. This movement causes the fluid medicament 303 to flowinto and through the hypodermic needle 308 until the upper dynamic seal302 approximates the lower dynamic seal 304 as illustrated in FIG. 16B.The fluid medicament 303 is thus moved from within the medicamentcontainment chamber 322 into the tissue targeted for dose delivery. Thespring force available from the partially biased needle insertion/fluidinjection spring 205 exceeds that of the compressed needle retractionspring 305. Thus the lower dynamic seal 304, the retainer 306 and thehypodermic needle 308 remain in their distal-most position throughoutdelivery of the fluid medicament 303.

FIG. 18 illustrates disengagement of the plunger rod 209 at the end ofthe dose delivery. The complete mechanism is shown in FIG. 18A.Referring to FIG. 18B, as the spring rest 207 and the coupler 208 traveldistally and arrive at the opening of the housing counterbore 234, thecoupler 208 is no longer confined radially by the bore 226 of thehousing 206. As illustrated in FIG. 18C, (a section of FIG. 18D), theannular engaging surface 230 of spring rest 207, contacting the coupler208 on a radially interior point as previously described, urges thecoupler 208 radially outward, thus disengaging the coupler 208 frominvolvement with plunger rod groove 231. Upon disengagement, the coupler208 is permanently captured within the housing counterbore region 234confined by the housing 206, the spring rest 207 and the syringe bodyretaining surface 334. Upon disengagement of the coupler 208 from theplunger rod groove 231, the needle insertion/fluid injection spring 205no longer exerts any influence on the plunger rod 209.

FIG. 19 illustrates the automatic injection and retraction syringe 100,less the cap 309, transitioning from termination of the involvement ofthe coupler 208 and the plunger rod 209 as shown in FIG. 19A to thestate whereupon the plunger rod 209, the upper dynamic seal 302, thelower dynamic seal 304, the retainer 306 and the hypodermic needle 308have been retracted as illustrated in FIG. 19B. Upon decoupling of thecoupler 208 from the plunger rod 209 as described in the previousparagraph, the energized needle retraction spring 305 exerts aproximally directed force upon the lower dynamic seal 304 via theretainer 306 sufficient to overcome the dynamic friction of the upperdynamic seal 203 and lower dynamic seal 304 in sliding contact againstthe interior surface of the syringe body 301. The upper dynamic seal 302and the lower dynamic seal 304, the plunger rod 209, the retainer 306and the hypodermic needle 308 are thus urged proximally until distaltravel is terminated by the retainer barb 317 contacting the distal-mostportion of the syringe body 301. Once retracted, the hypodermic needle308 is shielded from exterior access due to the tip being retractedwithin the nose aperture 331 a safe distance. The hypodermic needle 308remains permanently retracted due to continual force applied to theretainer 306 by partially biased needle retraction spring 305.

Referring back to FIG. 18 b , at the end of its travel and afterdisengagement from the plunger rod 209, the spring rest 207 remainsstationary in its final position, forced in the distal direction by thepartially biased needle insertion/fluid injection spring 205 andrestrained from further distal movement due to the coupler 208 boundagainst the retaining surface 334 of the syringe body 301.

Referring to FIG. 22 , and as mentioned previously, one preferred methodfor installing the fluid medicament 303 into the automatic injection andretraction syringe 100 is accomplished by securing a fluid transfermechanism 400, for example, a conventional Luer slip syringe asillustrated in FIG. 22A, into engagement with the female socket 311 toform a pressure tight connection as shown in FIG. 22B. Alternatively, apiston pump or peristaltic pump could be used for fluid transfer. Atfactory assembly and prior to filling, the upper dynamic seal 302 ispositioned in close proximity to the lower dynamic seal 304. As thefluid medicament 303 is urged to flow out of the fluid transfermechanism 400, seals established through engagement of the cap seal 310about the hypodermic needle 308 and the taper lock engagement betweenthe fluid transfer mechanism 400 and female socket 311 forces the fluidmedicament 303 to flow into the distal end of the hypodermic needle 308.Under continued pressure imposed upon the fluid medicament 303 by thefluid transfer mechanism, fluid medicament 303 flows through thehypodermic needle 308 and enters the medicament containment chamber 322.Exploiting the low friction, dynamic sealing properties of the upperdynamic seal 302 in sliding contact with the syringe body 301, and byvirtue of the buttress surface 315 preventing distal movement of theretainer 306 and lower dynamic seal 304, continued application ofpressure upon the fluid medicament 303 through the fluid transfermechanism urges the upper dynamic seal 302 in the proximal directionuntil the desired dose volume is transferred into the medicamentcontainment chamber 322 as illustrated in FIG. 22C. The fluid transfermechanism 400 is thereafter removed from engagement with the cap 309 asillustrated in FIG. 22D. Optionally, e.g. a scenario where automaticinjection and retraction syringe 100 is not used immediately; the plug321 is thereafter installed in the female socket 311 as illustrated inFIG. 22E.

Referring to FIG. 23 , a second preferred method for conveyingmedicament into the present invention is described. The lowersubassembly 300, preferably in a sterile condition, is provided absentthe upper dynamic seal 302. Preferably, the lower subassembly 300, whichincludes pre-installed plug 321, is presented in a vertical orientationwith the open, distal end of syringe body 301 disposed upwardly. Asillustrated in FIG. 23A, the fluid medicament 303 is dispensed into theopen end of the syringe body 301 via a fill nozzle 500 allowing gravityto carry the fluid medicament 303 into the syringe body 301. Afterwards,as illustrated in FIG. 23B, the upper dynamic seal 302 is inserted intothe open bore of the syringe body 301 distal to the dose of fluidmedicament 303 as, for example, using a push rod 600. Assembly of theupper dynamic seal 302 into the syringe body 301 may be, as alternativecompleted under low atmospheric pressure conditions. Preferably, fillingof the fluid medicament 303 and placement of upper dynamic seal 302 areconducted under aseptic conditions. Several options for gravity fillingof medicament and dynamic seal placement are widely known to thoseskilled in the art. After placement of the upper dynamic seal 302 intothe syringe body 301, the upper subassembly 200 is permanently securedto the medicament-filled lower subassembly 300 to complete automaticinjection and retraction syringe 100.

Referring back to the figures and in particular to FIGS. 24 through 38 ,an alternative embodiment of an automatic injection and retractionsyringe according to the present disclosure is shown and hereinafterreferred to as syringe 700. The syringe 700 is generally symmetric aboutits long axis. Although there are many commonalities in structure,components and function shared between the syringe 700 and the aforedescribed embodiment of an automatic injection and retraction syringe100, the reference numerals used to describe the alternative embodiment,its constituents and features will be shown as unique to the alternativeembodiment for the purpose of distinction and clarity.

Referring to FIG. 24 , syringe 700 is shown pictorially in a statewherein the medicament is onboard and syringe 700 is ready to bedeployed by the user. Referring to FIG. 25 , the syringe 700 isgenerally symmetric about its long axis. Upon actuation, the syringe 700is adapted to automatically extend a hypodermic needle 716 from withinthe syringe 700 into tissue at an injection site, displace the fluidmedicament 714 through the hypodermic needle 716, and thereafter retractthe hypodermic needle 716 into the syringe 700. FIG. 25A is a top viewof the syringe 700, showing the cross section taken and displayed asFIG. 25B.

As similarly used to describe the first preferred embodiment, a generalaspect of operation of this second preferred embodiment is therelationship between the viscosity of the fluid medicament 716, theinner diameter of the hypodermic needle 716, the force applied upon thedynamic seal 712 by the needle insertion/fluid injection spring 706 byway of the plunger rod 707, the force of the retraction spring 718 uponthe medicament container 715, and the friction force resisting movementof the medicament container 715 within the bore of the outer housing713. The friction forces must be sufficiently low, the bore of theneedle 716 sufficiently small, the force of the retraction spring 718sufficiently low as compared to the force of the needle insertion/fluidinjection spring 706, and the viscosity of the fluid medicament 714sufficiently high so that the dynamic seal 712, the medicament container715, the fluid medicament 714, and the hypodermic needle 716 will, underthe influence of a released and fully energized needle insertion/fluidinjection spring 706 acting upon the plunger rod 707, traverse distallyto the end stop position before the fluid medicament 714 escapes thehypodermic needle 716.

Referring to FIGS. 25, 26A and 26B, an embodiment provides aself-retracting mechanized syringe 700 comprising a distally disposedtrigger in the form of a button 701, a button retainer seal 702, abutton retainer 703, a latch 704, a needle insertion/fluid injectionspring 706, a plunger rod 707, a spring rest 708, at least one coupler709, an inner housing 710, an inner housing cap 711, a dynamic seal 712,an outer housing 713, a medicament container 715, a hypodermic needle716, a cap 717, a retraction spring 718, a needle seal 719, and a capplug 720. Upon assembly of syringe 700, the needle insertion/fluidinjection spring 706 resides in a state of substantially fullcompression, axially coincident with and exterior to the plunger rod707. The needle insertion/fluid injection spring 706 is confined axiallyat one end by a distally disposed buttress surface 721 of the innerhousing 710 and at the other end by a proximally disposed bearingsurface 722 of the spring rest 708. The needle insertion/fluid injectionspring 706 is confined radially by the bore 723 of the inner housing710. Referring to FIG. 26B, the latch 704 provides retaining feature 724that engages with resting surface 725 disposed about the plunger rod 707to retain the needle insertion/injection spring 706 in an energizedstate until engagement between the plunger rod 707 and the latch 704 isdefeated by sufficient axial force applied in the distal direction uponthe button 701 while the button 701 is in the activated condition. Thelatch 704 and the inner housing 710 are preferably separate componentsbut may, alternatively, be consolidated into a single component withinthe scope of the claims.

Referring to FIGS. 27A through 27C which further describe an alternativeembodiment syringe 700, a button 701 resides with a portion exposed tothe exterior of the syringe 700 and a portion interior to the syringe700. The button 701 is captured in a coaxial relationship with andinternal to the button retainer 703 and cooperates in a rotatable andaxially slideable relationship with the button retainer 703. The buttonretainer 703 provides at least one button retainer slot 726 whichcooperates with a corresponding button arm 727 radially disposed on thebutton 701. The button arm 727 protrudes radially sufficiently so as tonest into the button retainer slot 726. By virtue of physicalinterference, the button retainer slot 726 presents limitations to themovement of the button arm 727 within the button retainer slot 726. Tothis end, the button retainer slot 726 is configured to allow the buttonarm 727 to rotate about its long axis in relation to the button retainer703 from a first rotational position as shown in FIG. 27A to a secondrotational position as shown in FIG. 27B. The first position shown inFIG. 27A corresponds to a functional state wherein the button 701 isprevented from axial, distal movement and the second state shown in FIG.27B corresponds to a functional state wherein the button 701 is allowedaxial, distal movement. A slot tip 728 is disposed on the surface of thebutton retainer slot 726 and configured to present a slight interferenceto radial motion of the button 701 as it rotates from the first state tothe second state. The physical properties of the button retainer 703 arepreferably semi-rigid allowing deflection of the slot tip 728 as thebutton 701 moves from the first position to the second position. Oncethe button 701 is rotated into the second position, deflection of theslot tip 728 terminates and the slot tip 728 returns to its natural,unbiased condition. Once button 701 is rotated to the second positionwherein the slot tip 728 is freed from contact with the button arm 727,a buttress surface 729, disposed on the slot surface, imposes a physicalinterference with the button arm 727 which disallows the button 701 toreturn from the second position back to the first position. At least oneflatted and radially disposed gripping surface 730 is presented upon thebutton 701 providing fingertip leverage that facilitates rotating thebutton 701 from the first position to the second position. Once thebutton 701 is rotated from the first position to the second position,the button arm 727 is confined to axial movement within the buttonretainer slot 726; an axial, distal force applied to the button willthen cause the button to translate distally from the second positionshown in FIG. 27B to a third position shown in 27C.

The first position described above corresponds to a “safety on”condition of the syringe 700 in which the syringe 700 cannot beactuated; the second position described above corresponds to a “safetyoff” condition in which the syringe 700 can be actuated. Preferably, thebutton arm 727 is visible through the button retainer slot 726 whichallows the visible portion of the button arm 727 to serve as a visualindicator of the “locked” vs. “unlocked” status. As described in FIG. 24, preferably, recognizable iconic graphics 731 denoting a “locked” andan “unlocked” condition are provided on the exterior surface of thesyringe 700 at either end of the slot through which the button arm isvisible and wherein the button arm is allowed rotational movement; the“locked” graphic being disposed adjacent to the first position and the“unlocked” graphic being disposed adjacent to the second position.Referring to FIGS. 24 and 25 , graphics 731 may be incorporated into alabel 705 attached about the periphery of the outer housing 713.

Referring to FIG. 26A and FIG. 26B, an elastomeric button retainer seal702 is preferably provided. The button retainer seal 702 resides in acompressive condition interfering radially with the exterior surface ofbutton 701 and inwardly disposed surface of button retainer 702 therebyinhibiting air exchange between the interior and exterior of the syringe700. Button retainer seal 702 cooperates with the button 701 allowingboth rotational and axial movement of the button 701 relative to thebutton retainer seal 702. The button retainer 703 is permanentlyretained within the outer housing 713 preferably by way of interferencesnap fit as exemplified in FIG. 26B by the button retainer snap fitfeature 732 and outer housing snap fit feature 733. Alternatively,button retainer 703 may be permanently retained within the outer housing713 by means of ultrasonic welding, solvent bonding, adhesive bonding,or other common bonding methods known those skilled in the art.

Notwithstanding the foregoing, button functionality and in particularthe role of cam 734 and its relationship with latch finger 735 are asdescribed previously in this disclosure.

Referring to FIGS. 28A and 28B, a medicament container 715, a dynamicseal 712 and a hypodermic needle 716 provide a storage compartment forthe fluid medicament 714. The medicament container 715 and thehypodermic needle 716 are permanently bonded together as a subassemblywith the proximal opening of the hypodermic needle 716 in open fluidcommunication with the interior of the medicament container 715. Bondingis preferably accomplished by way of an adhesive. Alternatively, thehypodermic needle 716 may be molded into the medicament container 715. Adistal facing syringe buttress surface 736 is disposed about theperiphery of medicament container 715. The medicament container 715provides a distally facing buttress surface 736. The buttress surface736 cooperates with a corresponding rib shoulder 737 internally andproximally disposed within outer housing 713 to arrest axial travel ofmedicament container 715 travelling distally under the influence ofenergized needle insertion/fluid injection spring 706. In addition toarresting distal travel of the medicament container 715, the ribshoulder 737 defines a datum by which the distance the hypodermic needle716 extends beyond the distal end of syringe 700 upon actuation andsubsequent needle insertion can be established and controlled.Similarly, the rib shoulder 737 establishes a known axial location ofthe proximally-facing interior surface 738 of the medicament container715 in relation to the distal end 739 of the inner housing 710 to assurethat the coupler 709 exits the distal end 739 of the inner housing 710and disengages from the plunger rod 707 as the dynamic seal 712approximates the proximally-facing interior surface 738 of themedicament container 715.

Again referring to FIG. 28B, a proximally disposed counterbore shoulder741 disposed about the interior surface of the outer housing 713provides a buttress surface upon which the distal end of the innerhousing cap 711 resides after assembly of the syringe 700. Referringback to FIG. 26B, the proximal end of the inner housing 710 is securedaxially by contact with the proximal surface 742 of the latch 704 andthe distal surface 743 of the button retainer 703.

Referring to FIGS. 29A and 29B, a cap plug 720 is described. Thefunction of cap plug 720 is as described previously herein and infunction is comparable to the plug 321, i.e. it serves to close thedistal end of the syringe 700 once the fluid medicament 714 is conveyedinto the medicament container 715 through the hypodermic needle 716.Preferably, the elastomeric or semi-elastomeric cap plug 720 is attachedto the cap 717 via an annular ring 744 which when assembled with the cap717 resides within a corresponding receiving groove 745 disposed aboutthe periphery of the distal end of the cap 717. A flexible hinge 746connect the cap plug body 747 to the annular ring 744 thus retaining thecap plug 720 in direct assembly with the cap 717 and allows the cap plugbody 747 to swing into engagement with the female socket 748 disposed atthe distal end of the cap 717.

FIGS. 30 through 35 describe the operational sequence of an alternativeembodiment (syringe 700) after it has been loaded with fluid medicamentand illustrate particularly noteworthy states or transitional states inthe operational sequence. FIGS. 30A through 30C are cross sectionalviews of the syringe 700 and depict the cap 717 being removed from thefilled syringe 700. FIG. 30A is a cross-sectional view of syringe 700filled with fluid medicament 714 and ready for deployment.

FIG. 30B illustrates removal of the cap 717 effectuated by applicationof a distally-directed force applied upon cap 717 while holding thefilled syringe 700 stationary. FIG. 30C illustrates the syringe 700 withthe cap 717 removed.

FIGS. 31A through 31C illustrate the medicament-filled syringe 700, lessthe cap 717, as it transitions from an un-activated to activated state.FIG. 31A illustrates a portion of an exterior prospective view of themedicament-filled syringe 700 in the “locked” position. The visiblesurface of the button arm 727 is shown adjacent to the “locked” graphic.FIG. 31B illustrates the same exterior prospective view of themedicament-filled syringe 700 once the button 701 is rotated from the“locked” position to the “unlocked” position. By example, moving thebutton 701 from the “locked” to the “unlocked” position is accomplishedby gripping the syringe outer housing 713 with one hand while graspingthe button 701 with the thumb and forefinger of the other hand androtating the button 701 counterclockwise about its axis from the“locked” to the “unlocked” position.

FIGS. 32A and 32B illustrate the medicament-filled syringe 700, less thecap 717, as it transitions from an activated state in which the button701 has been moved from the “locked” to the “unlocked” position, asdescribed above, to an actuated state in which the button 701 has beenforced in the distal direction sufficiently to have the cam 734 disposedon the button 701 engage with and pry open the latch finger 735 therebyreleasing the plunger rod 707.

FIGS. 33A and 33B illustrate the medicament-filled syringe 700, less thecap 717, as it transitions from the actuated state described in FIG. 32Bto the state whereupon the hypodermic needle 716 is fully extended asdescribed in FIG. 33B. Upon release of the plunger rod 707 duringactuation the needle insertion/fluid injection spring 706 acts upon thespring rest 708 and, by virtue of the relationship between the springrest 708, the coupler 709, and the plunger rod 707 described previouslywithin this disclosure, the plunger rod 707 is driven distally andimpinges upon the dynamic seal 712. As the needle insertion/fluidinjection spring 706 extends and forces the plunger rod 707 in thedistal direction, and due to the incompressible nature of the fluidmedicament 714, the assembly comprising the medicament container 715,the dynamic seal 712, the hypodermic needle 716, and the fluidmedicament 714 translate distally until the medicament container 715abuts the proximally disposed rib shoulder 737 of the outer housing 713.As the medicament container 715 traverses this distance, and due to therelative weakness of the retraction spring 718 compared to the strengthof the needle insertion/fluid injection spring 706, the retractionspring 718 compresses from a first, partially biased state to a second,more significantly biased state.

FIGS. 34A and 34B illustrate the syringe 700, less the cap 717,transitioning from the needle-inserted state as described in FIG. 34A tothe state whereupon fluid medicament 714 is fully dispelled from thesyringe 700 as shown in FIG. 34B. Upon termination of the travelsequence described in the above paragraph, the medicament container 715and attached hypodermic needle 716 remain stationary. The dynamic seal712, under the continued influence of the needle insertion/fluidinjection spring 706 imposing a force upon the plunger rod 707 asdescribed previously, continues movement in the distal direction. Thismovement causes fluid medicament 714 to flow into the proximal opening749 of the hypodermic needle 716, through the hypodermic needle 716 andinto the target tissue at the injection site. Flow of the fluidmedicament 714 continues until the dynamic seal 712 approximates theproximally-facing interior surface 738 of the medicament container 715as illustrated in FIG. 34 b thereby effectuating dose delivery. Thespring force available from the partially biased needle insertion/fluidinjection spring 706 exceeds that of the compressed needle retractionspring 718 even at the end of dose delivery; the medicament container715 thereby remains stationary at its distal-most allowable positionthroughout the delivery of the fluid medicament 714.

FIGS. 35A through 35D illustrate disengagement of the coupler 709 fromthe plunger rod 707 at the end of dose delivery. Referring to FIGS. 35Aand 35B, as the spring rest 708 and the coupler 709 travel distally andexit the distal opening 740 of the inner housing 710, the coupler 709 isno longer confined radially by the bore 723 of the inner housing 710. Asillustrated in FIG. 34B, the annular engaging surface 750 of the springrest 708 contacting the coupler 709 on a radially interior point of thecoupler 709 as previously described. The applied force imposed upon thecoupler 709 by the spring rest 708 thus includes a radially outwardlydirected force component. This outwardly directed force component urgesthe preferably spherical coupler 709 radially outward into contact withthe bore 723 of the inner housing 710. The outwardly directed forcecomponent is a function of the sine of the contact angle measuredbetween a line through the coupler 709 center and parallel to the longaxis of the syringe 700 and a line from the coupler 709 center to thepoint of contact between the coupler 709 and the spring rest 708. Thusas the coupler 709 resides within the bore 723 of the inner housing 710,it remains in contact with the bore 723 of the inner housing 710, thespring rest 708, and the plunger rod 707. As the fluid medicament 714 isdelivered the plunger rod 707, the spring rest 708 and the coupler 709travel distally and in tandem along within the bore 723 of the innerhousing 710. Upon arrival at the distal opening 740 of the inner housing710, the coupler 709 escapes the bore 723 of the inner housing 710 andthe radial force constituent applied upon the coupler 709 by the springrest 708 urges the coupler 709 radially outward. As the coupler 709begins to move radially outward under the influence of the spring rest708, the contact angle increases thus increasing the radial component ofthe applied force until full separation of coupler 709 from the plungerrod 707 occurs. As illustrated in FIGS. 35C and 35D, once the coupler709 escapes the bore 723 of the inner housing 710, the coupler 709disengages from the plunger rod 707 and the coupler 709 becomes trappedwithin the inner housing cap 711. The coupler 709 thereafter remainspermanently retained within the inner housing cap 711 by the spring rest708 which remains under the influence of the partially biased needleinsertion/fluid injection spring 706.

FIGS. 36A and 36B illustrate the syringe 700, less the cap 717transitioning from termination of the involvement of the coupler 709 andthe plunger rod 707 as shown in FIG. 36A to a state whereupon theplunger rod 707, dynamic seal 712, medicament container 715 andhypodermic needle 716 have been forced proximally by the energizedretraction spring 718 into a retracted state as illustrated in FIG. 36B.As illustrated in FIG. 36A, the energized retraction spring 718 exerts aproximally directed force upon the medicament container 715. Upondecoupling of the coupler 709 from the plunger rod 707 as described inthe previous paragraph, the needle insertion/fluid injection spring 706no longer exerts any influence upon the plunger rod 707. Given that themedicament container 715 is preferably dimensioned for an easy runningfit within the outer housing bore 751, the biased retraction spring 718therefore urges the plunger rod 707, the dynamic seal 712, themedicament container 715 and the hypodermic needle 716 in the proximaldirection until the proximal end of the medicament container 715 abutsthe distal surface 753 of the inner housing cap 711 as illustrated inFIG. 36B. In this final condition, the sharp tip 754 of the hypodermicneedle 716 is retracted sufficiently within the distal aperture 755 ofthe outer housing 713 that it is rendered inaccessible and does notthereafter represent a risk of needle stick injury.

Referring to FIGS. 38A through 38E, and as similarly described in theprior embodiments; one preferred method for installing the fluidmedicament 714 into the syringe 700 is accomplished by securing a fluidtransfer mechanism 400, for example a conventional Luer slip syringe asillustrated in the figure, into engagement with the female socket 748provided at the distal end of cap 717 to form a pressure tightconnection as shown in FIG. 38B. Alternatively, a piston pump orperistaltic pump could be used for fluid transfer. At factory assemblyand prior to filling, the dynamic seal 712 is positioned in closeproximity to the proximally-facing interior surface 738 of themedicament container 715. As the fluid medicament 714 is urged to flowout of the fluid transfer mechanism 400, seals established throughengagement of the needle seal 719 about the hypodermic needle 716 andthe liquid tight engagement between the fluid transfer mechanism 400 andthe female socket 748 forces the fluid medicament 714 to flow into thedistal end of the hypodermic needle 716. Under continued pressureimposed upon the fluid medicament 714 by the fluid transfer mechanism400, the liquid medicament 714 flows into the space between the distalend of the dynamic seal 712 and medicament container 715 via thehypodermic needle 716 in a direction opposite to that of the directionof fluid flow that occurs during dose delivery. Exploiting the lowfriction dynamic sealing properties of the dynamic seal 712, continuedapplication of pressure upon the fluid medicament 714 via the fluidtransfer mechanism 400 urges the dynamic seal 712 in the proximaldirection until the desired dose volume is transferred into the internalvolume of the medicament container 715 distal to the dynamic seal 712and proximal to the hypodermic needle 716 as illustrated in FIG. 38C.The fluid transfer mechanism 400 is thereafter removed from engagementwith the cap 717 as illustrated in FIG. 38D. Optionally, e.g. a scenariowhere the medicament-filled syringe 700 is not used immediately; the capplug 720 is installed as previously described in the female socket 748as illustrated in FIG. 38E.

None of the description in this application should be read as implyingthat any particular element, step, or function is an essential elementwhich must be included in the claim scope; the scope of patented subjectmatter is defined only by the allowed claims. Moreover, none of theseclaims are intended to invoke 35 U.S.C. Section 112(f) unless the exactwords “means for” are used, followed by a gerund. The claims as filedare intended to be as comprehensive as possible, and no subject matteris intentionally relinquished, dedicated, or abandoned.

The invention claimed is:
 1. A method for transferring a medicinal fluidinto a drug delivery device comprising: attaching onto the drug deliverydevice in a sealed relationship a fluid transfer device containing themedicament to be transferred wherein the drug delivery device isattached to the fluid transfer device by coupling a first Luer taper ofthe fluid transfer device with a second Luer taper of the drug deliverydevice; conveying, by application of a force to an actuator of the fluidtransfer device, the medicament from the fluid transfer device into thedrug delivery device, wherein the medicament is conveyed from the fluidtransfer device into the drug delivery device through a hypodermicneedle constituent of the drug delivery device, and wherein thehypodermic needle of the drug delivery device delivers the medicamentinto tissue at an injection site; and thereafter terminating the sealedrelationship between the fluid transfer device and the drug deliverydevice by separating the first Luer taper and the second Luer taper. 2.A method as described in claim 1, where the drug delivery device furthercomprises an inlet; the method further comprising: plugging the inletafter the medicament is transferred into the drug delivery device andthe fluid transfer device is removed from sealed connection with thedrug delivery device.
 3. An apparatus for injection of a liquidmedicament, comprising: a housing; a drug containment chamber disposedinternally to the housing and providing a volume for storage of a liquidmedicament; a slideable piston disposed proximal to the drug containmentchamber; a spring disposed within the housing, the spring configured toapply force upon the piston upon release of the spring; a releasablelatch configured to selectively release the spring; a removable capdisposed about the housing and releasably connectable to the housing,the removable cap including an inlet exposed at an exterior of theapparatus when the apparatus is fully assembled, wherein the inlet isdimensioned to be compliant with a female Luer taper; a hypodermicneedle including a first end in fluid communication with the drugcontainment chamber and a second end in fluid communication with theremovable cap inlet; and the removable cap further providing a slideableand liquid-tight seal with the hypodermic needle.
 4. A kit for preparingan apparatus for injection of a liquid medicament, the kit comprising:the apparatus comprising: a housing; a drug containment chamber disposedinternally to the housing and providing a volume for storage of a liquidmedicament; a slideable piston disposed proximal to the drug containmentchamber; a spring disposed within the housing, the spring configured toapply force upon the piston upon release of the spring; a releasablelatch configured to selectively release the spring; a removable capdisposed about the housing and releasably connectable to the housing,the removable cap including an inlet exposed at an exterior of theapparatus when the apparatus is fully assembled, wherein the inlet isdimensioned to be compliant with a female Luer taper; a hypodermicneedle including a first end in fluid communication with the drugcontainment chamber and a second end in fluid communication with theremovable cap inlet; and the removable cap further providing a slideableand liquid-tight seal with the hypodermic needle; and a pre-filledsyringe holding a liquid medicament, wherein the pre-filled syringe isdimensioned to be compliant with a male Luer taper to make aliquid-tight connection with the female Luer taper.
 5. The kit of claim4, where the liquid-tight connection is accomplished by the mating ofLuer tapers.
 6. The method of claim 1, wherein the actuator of the fluidtransfer device is a plunger, and wherein conveying the medicamentfurther comprises actuating the plunger of the fluid transfer device toexpel the medicament from the fluid transfer device and into the drugdelivery device.
 7. The method of claim 1, wherein conveying themedicament further comprises reducing an internal volume of the fluidtransfer device to expel the medicament from the fluid transfer deviceand into the drug delivery device.